1. Field of the Invention
This invention relates to interpolymers of monomers comprising a major amount of: (a) one or more polar monomers such as an alkyl acrylate and (b) one or more olefins such as propylene. Optionally, the interpolymers of this invention may incorporate in the macromolecule a minor proportion of (c) one or more acyclic or alicyclic conjugated or nonconjugated diolefins such as butadiene or dicyclopentadiene. More particularly, this invention relates to interpolymers of said monomers prepared with a catalyst system comprising a Lewis acid, an organic peroxide and optionally, a vanadium compound. Most particularly, this invention relates to a process for the preparation of interpolymers of said monomers with the aid of said catalysts wherein the polar monomer is complexed with the Lewis acid in a first stage at a "low temperature" in the range of .about. -100.degree.C to .about.0.degree.C; or, if complexed at a higher temperature with said Lewis acid, it is cooled to the "low temperature", admixed at said low temperature with the olefinic monomers and remainder of the components comprising the catalyst system and maintained at said low temperature for a time sufficient to convert not less than about 10 percent nor more than about 50 percent of the polar monomer originally fed to the reaction mixture to interpolymer; thereafter raising the temperature of the reaction mixture to a "higher temperature" in the range of .about.0.degree.C to .about.100.degree.C, maintaining said reaction mixture at said "higher temperature" for a time sufficient to optimize conversion of the remainder of the monomers to interpolymers and recovering said interpolymers from the reaction mixture.
Polymers prepared in accordance with this invention have high molecular weights as evidenced by inherent viscosities in the range of .about.0.5 to .about.6.0 when measured in benzene at 25.degree.C at a concentration of 0.1 G/DL, and depending on the starting monomers are useful in varying applications.
Interpolymers prepared for example from a C.sub.1 to C.sub.6 alkyl acrylate such as ethyl acrylate, a C.sub.2 to C.sub.8 monoolefin such as isobutene and up to .about.10 mole percent of a diolefin such as butadiene yield elastomeric interpolymers which when vulcanized with sulfur or sulfur compounds exhibit high modulus, good tensile strength and resistance to oil, solvents and heat aging. Polymers made for example from acrylonitrile, styrene and butadiene or from methyl methacrylate and styrene yield thermoplastic resins; and polymers made from higher, preferably straight or branched chain, alkyl acrylates and higher, preferably straight chain, alpha olefins have good oil solubility and act as oil thickeners, viscosity index improvers and sludge dispersants when incorporated in lubricating oil compositions.
2. Description of the Prior Art
Since the original work in the laboratories on the preparation of alternating interpolymers of polar monomers and olefinic monomers using Lewis Acid -- peroxide catalyst systems disclosed in U.S. Pat. Nos. 3,183,217; 3,278,503; and 3,426,005. There has been extensive work published in both the patent and technical literature. See for example the discussion on prior art in the parent application above referred to and in my copending U.S. Patent Application Ser. No. 459,865 (filed Apr. 11, 1974), which is herein incorporated by reference. See also Abstract 49, by N. G. Gaylord, 163rd ACS Meeting, Boston, Apr. 1972.